i) Field of the Invention
This invention relates to a dock seal device for loading dock openings in a wall and to seal elements of such a device, more especially the invention is concerned with an inflatable dock seal device and inflatable dock seal elements.
ii) Description of the Prior Art
Inflatable dock seals are known from U.S. Pat. Nos. 3,303,615; 3,714,745 (Canadian Patent No. 958,946); 3,391,502 (Canadian Patent No. 844,999) and 3,391,503 (Canadian Patent No. 844,877) all of Larry O'Neal, and from U.S. Pat. No. 3,994,103 (Canadian Patent No. 1,079,125) of Wilfred Ouellet. These generally comprise a top, hollow, flexible, inflatable, horizontal section and a pair of side, hollow, inflatable, vertical sections arranged about a loading dock opening. These sections may constitute three separate members independently mounted about the opening with their interiors in air flow communication as described in U.S. Pat. No. 3,714,745 or they may constitute a single generally U-shaped member as shown in U.S. Pat. Nos. 3,303,615; 3,391,502; 3,391,503 and 3,994,103.
The dock seal devices serve to seal the loading area in which personnel operate from the external environment so that personnel are sheltered during poor weather. In addition the seal devices serve to prevent loss of heat from a heated building to a cold environment, and access to the building of cold air during winter, and conversely to prevent access of hot humid air to a cooled or air-conditioned building during summer.
Dock seals of the general type comprising separate members, such as shown in U.S. Pat. No. 3,714,745, have the advantage that the members can be spaced, at the time of installation, about the dock opening, so that they do not interfere or intrude into the entry passage in front of the opening, into and out of which a truck is to be brought into register for loading and unloading, and additionally they can be more readily adapted to different size openings.
As can be seen from FIGS. 3 and 4 in U.S. Pat. No. 3,714,745, the vertical side members inflate along an arcuate path or, otherwise stated, have an arcuate axis of inflation, whereby in the non-inflated or collapsed configuration shown in FIG. 3 of the Patent, the collapsed, vertical, side members are retracted away from the dock opening; and in the inflated configuration shown in FIG. 4, the free outer ends of the side members, which engage the truck, are spaced forwardly of the dock opening so as not to interfere or intrude into the loading area where there is a risk of damage to the flexible members such as by fork lift trucks operating in the loading area.
Disadvantages of dock seals of the general type shown in U.S. Pat. No. 3,391,503 are that the arcuate, inflated side members become floppy with increasing arcuate length and for practical purposes the arcuate length cannot exceed about 2 ft. Furthermore the gap between the arcuately inflated members and the wall of the opening produces an open bottom which reduces the sealing efficiency and permits access of heated air from the building to the atmosphere, and entry of cold air, in winter, or access of warm external air to a cooled environment within the building in summer. Loose ,flaps of sheet material are sometimes provided to bridge the gap and which must be manually fastened and unfastened before and after use to the wall, however, personnel tend to ignore them because of the inconvenience involved in assembling the flaps.
A disadvantage shared by all of the dock seals of the afore-mentioned Patents is that in sealing the opening they exclude natural light so that the loading area is often only dimly lit by artificial lights within the building which are often remotely spaced from the opening so that lighting is inadequate and the working environment uncomfortable.
Another disadvantage shared by all dock seal devices of the afore-mentioned Patents is that they have not addressed the problem of rain water or the like seeping between the horizontal seal section and the truck, into the loading area.
In the seal device of U.S. Pat. No. 3,714,745, the roof of the upper support is flat and inclined downwardly towards the truck as can be seen from FIGS. 2 and 5 of that Patent. Thus rain water flows from the flat roof onto the roof and sides of the truck and may seep between the truck and the seal members, particularly with movement of the truck to adjust its position.
In the seal devices of the other Patents, for example, U.S. Pat. No. 3,391,503 it can be seen that rain water will flow downwardly over the convex surface of the horizontal section.